As a technique relating to a mobile core network, a system that uses an SGSN (Serving GPRS (General Packet Radio Service) Support Node) and a GGSN (Gateway GPRS Support Node) as a device constituting a mobile core network can be exemplified. The SGSN is a node used for connecting to a radio access network. The GGSN is a node connected to an Internet service provider for Intent connection or a node connected to Intranet. The above system allows transmission/reception of packets to/from a mobile terminal through a base station on a mobile terminal network.
As a method concerning processing of a user plane packet transmitted in the above system, there is known a technique disclosed on, e.g., PTL 1. In the technique of PTL 1, the SGSN and GGSN each prepare an address table registering correspondence between an destination address and a transfer destination (SGSN) address, and the transfer destination of a packet is searched for using a destination set in the table as a key.